But fitting the Factory Toneau has similar features requiring a good fight and is fun (I mean easier) when SWMBO hanging onto the opposite side.

I can't believe that I said this! When I wrote it, I was thinking of the 4/4 'Lellow Car' experiences.
Yesterday was another story as I spent half an hour fighting with the UNTRIED Toneau on the Centenary Roadster 100.
What with my aching & hurting Thumb Joints, I eventually gave up. The B****y thing just will not fit across the width. It is too small by an absolute minimum of about 4cm and it will have to go back!
Being fundamentally a Tailor by training, I can see clearly that someone at the factory has fouled up with the Pattern Making so I guess none of them fit? I was at a Classic event yesterday (24th) where there were two Morgans with the old type and the fit was nice and 'Easy' as were those on some of the more vintage other cars.
It is obvious that they do not trial fit these before delivery or they would have found this out (a bit like the Luggage Rack that took them 3 goes to supply the right one).
Thanks for comments on the Sump Fix. I have tried to take some pic which I will post in a new thread. I am hoping that someone has a photo of the damaged sump before sending it away.